For Mexico, 2010 is a deeply symbolic year. Mexicans celebrate 200 years of independence from Spain and the 100th anniversary of the Mexican Revolution. Their government will spend $300 million on the party, but no amount of fireworks or revolutionary nostalgia can overcome the inescapable sensation that Mexico is sinking into crisis.

Drug-gang assassins recently massacred 72 Central and South American migrants. The two local and state investigators who first arrived at the crime scene disappeared and were found dead two weeks later. Gunmen killed three Mexican mayors in the past month.

In the first four years of President Felipe Calderón’s drug war, more than 28,000 people have been slain, according to the government’s own count. Yet there have been few prosecutions: less than 5 percent of these murders have been investigated. But even those who are inured to corruption and incompetence are sickened by news of a prison warden who let a death squad out at night over a period of months — driving official vehicles and armed with prison guard assault rifles — to massacre innocent people in a neighboring state.

Headlines from Mexico bleed with news of such brutal killings and government ineptitude. And even as the violence continues to build, a recession — spreading south from the United States — cuts to the economic bones of an already vulnerable Mexican population. Growing economic desperation and shocking violence have undermined Mexicans’ faith in the ability of their government to manage the economy, control the country’s streets, mete out justice, or even to remain neutral among the warring cartels seeking to control North America’s drug-trade corridors.

It sounds bad and thus it is tempting to turn our gaze away from the news of mayhem and sadistic acts of violence coming out of Mexico. But we must not, and cannot afford to, turn away. The well-being of Mexico is vital to the well-being of the United States. We are neighbors and economic partners who share a continent and a common destiny. Any effective prescription to pull Mexico back from the abyss will require cooperation — as well as introspection and substantive policy changes — from the United States.

The U.S. should openly join the conversation on strategic and selective decriminalization of drugs like marijuana and impose strict controls on gun sales along the U.S. side of our common border. Clearly, most of Mexico’s problems need to be solved in Mexico, by Mexicans, but these are two crucial steps we can take on our side of the border to reduce the flow of money and guns fueling Mexico’s drug mafias. This one-two punch would deliver a damaging blow to the criminal organizations terrorizing Mexico.

A consensus is jelling on both sides of the border that it is time to move beyond the prohibitionist dogmas that have shaped — and doomed — the drug “war” since its declaration by Richard Nixon in the early 1970s. In Mexico, a chorus of opinion leaders including former President Vicente Fox have forced open a long-pent-up debate on drug legalization. President Calderón recently made news by endorsing debate on this topic, even as he reassured Washington, D.C., of his own continued allegiance to the prohibition camp.

Americans are the prime customers for the narcotics produced in and shipped through Mexico. Despite 40 years and hundreds of billions of dollars spent on the drug war’s eradication and interdiction plans, prohibited drugs are easily available across the United States today. Their illegality assures the inflated profits that sustain criminal organizations.

This fall, Californians may pass a ballot measure to end marijuana prohibition. That would be an important step, but irrespective of California’s choice, it is our federal drug and gun policies that must evolve to aid Mexicans fighting to preserve the soul of their country.

Mexicans often ask why the U.S. doesn’t ban the assault weapons that can still be legally purchased on our side of the border. The lamentable answer: powerful gun lobbyists successfully defend the legal sale of “single-shot” assault rifles even as they are routinely smuggled into Mexico where a simple tweak renders them fully automatic and ready to fire hundreds of rounds per minute in the hands of drug-cartel assassins.

Eighty percent of the 75,000 guns Mexican authorities seized from criminals during the past three years came from the U.S. This fact underscores the need to reclassify control of gun sales along our frontier as a matter of national security.

Putting the squeeze on the pipeline of money and weapons that feed Mexico’s inferno would be the best Independence gift we could give Mexico. It would help more than any amount of guns, money, training and electronic spy data we might provide to Mexico’s unreliable Army and police.